This invention relates to voltage converters and, more particularly, to direct current (DC)-to-DC converters that include field-effect-transistor (FET) switching devices.
Typical large-scale-integrated (LSI) circuits require power sources that supply relatively small positive DC voltages such as +5 volts. In many system environments, relatively large DC voltages (for example, +24 volts or -24 volts) are available. Circuits are known for converting these relatively large DC voltages to the smaller values needed for powering LSI devices. These known circuits include, for example, asymmetrically conducting diode elements whose losses are relatively high and bipolar transistor switches whose speed of operation is relatively slow.
Currently, much effort in the electronics industry is being directed at developing so-called very-large-scale-integrated (VLSI) circuits. Some of the supplies for powering these circuits are designed to provide extremely low DC voltages (for example, +2.5 volts or even as low as +0.5 volts). Moreover, as the trend toward microminiaturization intensifies, it is becoming increasingly important that the converters for providing these low DC voltages be small, inexpensive and characterized by extremely low losses.
Accordingly, considerable efforts have been directed by workers in the field at trying to devise small, inexpensive and low-power-loss DC-to-DC converters. It was recognized that such converters, if available, would expedite the development of commercially feasible VLSI circuits.